Definition
Nanotechnology is the engineering of functional systems at the molecular scale.
Nanotechnology is the creation and use of materials or devices at extremely small scales. These materials or devices fall in the range of 1 to 100 nanometers (nm)
The dimensional range of 1 to 100 nm is referred as the nanoscale, and materials at this scale are called Nanocrystals or Nanomaterials.

APPROACHES TO NANOTECHNOLOGY
Top-down Approach
In the top-down process, technologists start with a bulk material and carve out a smaller structure from it.
This is the process commonly used today to create computer chips, the tiny memory and logic units, also known as integrated circuits that operate computers.

Bottom-down approach:
The bottom-up approach involves the manipulation of atoms and molecules to form nanostructures.
The bottom-up approach avoids the problem of having to create an ever-finer method of reducing material to the nanoscale size. Instead, nanostructures would be assembled atom by atom and molecule by molecule, from the atomic level up, just as occurs in nature.

How Do We Visualise Small Things.
The tools used to manipulate and control materials and systems at the nanoscale include:
Transmission electron microscope (TEM)

Beams of light are passed through a thinly sliced specimen.
Magnify up to a million times
Reveal the detailed structures inside cells
Produce 2D images.

Atomic force microscope (AFM)

Â¢ A fine ceramic or semiconductor tip moves over a surface much the same way as a photograph needle scans a record.
Scanning tunneling microscope (STM)
A beam of electrons move across a specimen and constructs an image showing details of its surface.
Â¢ Produces 3D images
Â¢ For high resolution surface topographical study of mainly biological specimens.

Carbon Nanotubes

Carbon Nanotubes are novel cylindrical macro molecules composed of carbon atoms in a periodic hexagonal arrangement.
Nanotubes are composed entirely of sp2 bonds.
Stronger than the sp3 bonds.
Look like sheets of graphite rolled up into tubes produced by passing electric current between two graphite Electrodes surrounded by Helium.

Nanoscale Devices and Integrated Nanosystems
Nanochip
- Currently available microprocessors use resolutions as small as 32 nm
- Houses up to a billion transistors in a single chip
- MEMS based nanochips have future capability of 2 nm cell leading to 1TB memory per chip

Nanoelectromechanical System (NEMS) Sensors

- NEMS technology enables creation of ultra small and highly sensitive sensors for various applications
- The NEMS force sensor shown in the figure is applicable in pathogenic bacteria detection

Lab on Chip
- A lab on chip integrates one or more laboratory operation on a single chip
- Provides fast result and easy operation
- Applications: Biochemical analysis (DNA/protein/cell analysis) and bio-defense

Lab-on-phone
- A standard cell phone can be converted into a portable blood diagnosis machine (UCLA).
- The phone modification is able to detect HIV, malaria and various other illnesses.
- The device works by analyzing blood cells that are placed on the integrated camera sensor and lit up with a tiny filtered light source.
- The light source exposes unique qualities in cells and from their the camera runs special software which interprets the data and determines the state of the cell structures.

Nanotechnology in Health Care
Â¢ Thermal ablation of cancer cells
- Nanoshells have metallic outer layer and silica core
- Selectively attracted to cancer shells either through a phenomena called enhanced permeation retention or due to some molecules coated on the shells
- The nanoshells are heated with an external energy source killing the cancer cells

Quantum Photonics
Quantum dots are nanometer-sized, inorganic crystals that create light when stimulated with photons or electrons.
Quantum dots have extraordinary electronic properties.
Quantum dots have previously been ranged in size from nanometers to Micronâ„¢s in diameter

Risks associated with Nanotechnology
Nano-built products may be vastly overpriced relative to their cost, perpetuating unnecessary poverty.
Criminals and terrorists could make effective use of the technology.
Nanotech weapons would be extremely powerful and could lead to a dangerously unstable arms race.

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